Flow Resistance Characteristics of Pulsating Turbulent Flow Through a 90° Bend

The characteristics of flow resistance in a pulsating turbulent flow through a 90° bend with a circular cross-section were investigated. Water was used as the working fluid to investigate a wide range of governing parameters experimentally. The Womersley n umber α varied from 10 to 50, the mean Reynolds number ReSUBta/SUB from 7000 to 22000, the oscillatory Reynolds number ReSUBos/SUB from 6000 to 14000 (the flow rate ratio η was 0.3-0.8), and the curvature radius ratios RSUBc/SUB were 2, 4, and 6. The pressure drop between 2 d (d : inside diameter) upstream and 4d downstream of the bend was measured and analyzed, assuming a quasi-steady flow. The effects of the non-dimensional flow parameters and curvature radius ratio on the flow resistance characteristics were investigated. The approxi mate expressions for the time mean value, amplitude, phase difference from the flow rate variation, and power losses were consistent with the experimental results, and were thus practically useful.